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Geofencing enter/exit events not firing consistently RRS feed

  • Question

  • Hello,

    While researching the new Geofencing feature available for apps within Windows 8.1 and have been receiving inconsistent results.  For my test application I am creating two Geofences and adding them to the GeofenceMonitor's list. 

    Both Geofences are being set with the following properties:

    MonitorStates = MonitoredGeofenceStates.Entered | MonitoredGeofenceStates.Exited

    SingleUse = false

    DwellTime = new TimeSpan(0,0,1)  - 1 second

    Geoshape = new Geocircle(<coordinates>, 100)  - 100 meter radius

    I am finding that the GeofenceStateChanged event always fires on my initial location and the GeofenceState is set to Entered.  However, this event does not always fire upon exiting the Geofence radius and is very inconsistent being triggered upon entering/exiting the range of my other Geofence.  I have roughly driving 40mph while performing these tests. 

    During testing Geofences as a Background task I am receiving very similar results. 

    I am performing my testing using a 64-bit Windows 8.1 Pro on a Microsoft Surface tablet.  I am connecting to WIFI using a Verizon 4G LTE mobile broadband device.

    Are there known issues with the accuracy of this feature and if not could someone please provide me with suggestions for receiving consistent results?  I appreciate any and all help!

    Thank you,

    Eric

    Wednesday, May 28, 2014 11:53 PM

Answers

  • Hi Eric,

    I don't believe the Surface has a GPS, so the location readings will not be very precise. The GeoFence accuracy will depend on the accuracy of the underlying GeoLocation.

    --Rob

    • Marked as answer by Anne Jing Monday, June 9, 2014 1:17 AM
    Thursday, May 29, 2014 11:04 PM
    Moderator
  • Hi Eric,

    Given that the geofences defined are 100m and that you are driving at 40 mph, this will not work in most cases. At this speed you are covering 17 meters per second, so the fences will be crossed in about 6 seconds. The check for geofences does not occur this frequently, so in most cases the trigger will not occur.

    There is a blog published that can help see what is happening:

    http://blogs.windows.com/windows/b/appbuilder/archive/2014/02/25/testing-and-debugging-your-geofencing-apps.aspx

    • Marked as answer by Anne Jing Monday, June 9, 2014 1:17 AM
    Saturday, May 31, 2014 2:32 AM

All replies

  • Hi Eric,

    I don't believe the Surface has a GPS, so the location readings will not be very precise. The GeoFence accuracy will depend on the accuracy of the underlying GeoLocation.

    --Rob

    • Marked as answer by Anne Jing Monday, June 9, 2014 1:17 AM
    Thursday, May 29, 2014 11:04 PM
    Moderator
  • Hi Eric,

    Given that the geofences defined are 100m and that you are driving at 40 mph, this will not work in most cases. At this speed you are covering 17 meters per second, so the fences will be crossed in about 6 seconds. The check for geofences does not occur this frequently, so in most cases the trigger will not occur.

    There is a blog published that can help see what is happening:

    http://blogs.windows.com/windows/b/appbuilder/archive/2014/02/25/testing-and-debugging-your-geofencing-apps.aspx

    • Marked as answer by Anne Jing Monday, June 9, 2014 1:17 AM
    Saturday, May 31, 2014 2:32 AM
  • Christina,

    Thanks, I wasn't aware there is a notable lapse in time between checks.  Is there a specific value for how much time passes between checks? 

    Eric

    Monday, June 9, 2014 6:15 PM